Chestnut blight, caused by Cryphonectria parasitica Murr. Barr, is the most serious disease of chestnut trees in Turkey on which several studies related to biological control were conducted. The aim of this study was to determine the cause of the occurrence of healing cankers on untreated chestnut trees and the role of carriers in the spread of hypovirulence by laboratory tests. | Turkish Journal of Agriculture and Forestry Turk J Agric For (2017) 41: 278-284 © TÜBİTAK doi: Research Article Natural dissemination of hypovirulent Cryphonectria parasitica strain used for biological control of chestnut blight 1, 2 3 1 1 1 Naciye Mükerrem ÇELİKER *, Cevdet KAPLAN , Ersin ONOĞUR , Barbaros ÇETİNEL , Dilek POYRAZ , Ayşe UYSAL 1 Plant Protection Research Institute, Bornova, İzmir, Turkey 2 Department of Plant Protection, Faculty of Agriculture, Siirt University, Siirt, Turkey 3 Department of Plant Protection, Faculty of Agriculture, Ege University, İzmir, Turkey Received: Accepted/Published Online: Final Version: Abstract: Chestnut blight, caused by Cryphonectria parasitica Murr. Barr, is the most serious disease of chestnut trees in Turkey on which several studies related to biological control were conducted. The aim of this study was to determine the cause of the occurrence of healing cankers on untreated chestnut trees and the role of carriers in the spread of hypovirulence by laboratory tests, and to discover the effect of some environmental factors (temperature and relative humidity) on the natural spreading of hypovirulence. The study was carried out in a chestnut grove where biological control studies of the disease had been performed in previous years. Bark samples were collected from healed cankers and 388 possibly hypovirulent isolates were obtained. Two of them that were white converted virulent isolates to hypovirulent ones, but others developed yellowish cream-colored mycelia and did not convert virulent isolates. dsRNA analysis was performed on randomly selected possible hypovirulent isolates collected from healed cankers. After the virus concentration had increased, dsRNA-positive reactions were obtained for of the isolates. Thirty-one possible hypovirulent isolates from Formicidae and Gastropoda did not convert virulent
